As you can see from the picture of the USB board, they just left one antenna lead empty. The other is
connected straight to a small swivel antenna. We will do basically the same thing - leave one PCB anteanna
in tact, and replace the other with an external jack. You could probably disconnect
both PCB antennas and just use the external antenna, but I wanted to maintain one for everyday use around the house.
Also, I connected the external antenna to each of the onboard leads, and neither seemed to give any better performance
than the other, so I suspect that it doesn't matter which one you use.
NOTE: Christophe Cattelain sent me the following info (Thanks!):
"It is not necessary anymore to open the whole card, one
can just remove the antenna cover, which is much less risky."
You can find pictures of what Christophe means here
1. remove the small capacitor
2. connect antenna lead to ANT3 lead
NOTE: Allan Knox gave me the following info (Thanks!):
"The methodology you used to put on your antenna was right on target, except
for one thing. You should have kept the series capacitor and moved it to
where you placed the solder bridge. There will be a T/R switch that chooses
between the two antennas for any given frame (diversity reception) and that
cap is needed to block the DC that biases the diodes. If you ever short the
output, or zap it with static, you may damage the card."
Noting this, you should move the capacitor to where I indicated a solder bridge should be. I originally tried this, but
the reception didn't seem as good. Notice that my images are from before this, so they don't exactly match this description.
I used an old piece of thinnet (10base2) wire because it is easy to find and no one wants it. Plus
it's 50 ohms, which we need. And best of all, it has a free connector on the end. I so cannot afford
$10 connectors from digikey.
Just solder it right on the card. You'll need to trim the gray plastic
case that snaps together to allow it to fit through. Don't trim too much, a little pressure from the
enclosure should provide some minor strain relief.
That should do it. You can use another peice of RG58 with BNC connectors to hook up to your antenna. If
you put a BNC jack on the antenna, you only need to get one adapter, a pass thru.